Aquarium aerator

ABSTRACT

An aerator for an aquarium which includes a venturi tube in the recirculating system at the water return side, air and water reservoirs located adjacent the venturi tube, a small passage carrying controlled amounts of air in the upper portion of the passage from the air reservoir and controlled amounts of water in the lower portion of the passage from the water reservoir, the passage having a discharge port opening to the restricted section of the venturi where the air enters the water forming tiny bubbles, and a manually adjustable control for adjusting the air/water ratio flow through the passage. The passage being dimensioned such that the water meniscus in the passage covers a substantial portion of the passage.

United States Patent 11 1 Ennis I AQUARIUM AERATOR [76] Inventor: BobbeyG. Ennis, 40975 Chiltern Drive, Fremont, Calif. 94538 [22] Filed: Aug.4, 1971 [21] Appl. No.: 168,808

52 US. Cl 261/6, 261/64 R, 261/71,

261/121 R, 261/D1G. 75, 210/169 51 1m.c1...., ..B01f3/04 581 FieldotSearch ..210/169; 261/64 R,

261/71, 121 R,D1G. 75,6

[56] References Cited V UNITED STATES PATENTS 2,050,771 8/1936 Wait26l/DIG. 75

[ June 12, 1973 Primary Examiner-TimR. Miles Assistant Examiner-PRichardL. Chiesa AttorneyJames R. Cypher 57 ABSTRACT An aerator for an aquariumwhich includes a venturi tube in the recirculating system at the waterreturn side, air and water reservoirs located adjacent the venturi tube,a small passage carrying controlled amounts of air in the upper portionof the passage from the air reservoir and controlled amounts of water inthe lower portion of the passage from the water reservoir, the passagehaving a discharge port opening to the restricted section of the venturiwhere the air enters the water forming tiny bubbles, and a manuallyadjustable control for adjusting the air/water ratio flow through thepassage. The passage being dimensioned such that the water meniscus inthe passage covers a substantial portion of the passage.

6 Claims, 9 Drawing Figures PATENIEDJUM 2am SHEEI '4 IF 4 BACKGROUND OFTHE INVENTION In order to provide sufficient quantities of oxygen in anaquarium to sustain fish it is necessary to add oxygen to the water,either by replacing the water or injecting air into the water by someapparatus. Pumps may be used to circulate the water through filtersoutside the aquarium and air may be added to this circulating water bymerely permitting the water to drop from a predetermined height in thesame manner as a waterfall. Such systems obviously generate a fairamount of audible sound.

In other systems, air is introduced by connecting an air hose to aventuri tube which is connected to the discharge line of therecirculating system. This system introduces great quantities of air inthe form of air bubbles which are large and uncontrolled as to size.These bubbles rise to the surface of the aquarium and burst in acontinuous series of popping noises. Although the sound of the burstingbubbles is not loud, it is irritating to some persons who must work inquiet reception rooms and other places where aquariums are located.

SUMMARY OF THE INVENTION The gist of this invention is the discoverythat the size of air bubbles can be controlled and tiny bubbles can beformed by introducing water and air through a small passage so that theair enters the water through a meniscus rather than directly at awater/air interface where surface tension is much higher.

An object of the present invention is to provide an attachment which canbe directly connected to standard circulating pumps for aquariumswherein the tiny bubbles breaking at the surface make little more soundthan that created by a newly opened bottle of a carbonated beverage.

A further object of the present invention is to provide a device toaerate aquariums which is inexpensive to manufacture, can be connectedto existing aquarium equipment, has only one moving part and is nearlysilent in operation.

A further object is to provide an aerator which permits the bubble sizeto be regulated.

A further object is to provide an aerator which requires no replacementmaterials, is nearly maintenance free and will last the life of theaquarium.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross sectional view ofthe device constructed in accordance with the present invention takensubstantially along line 1-1 of FIG. 3. The device is shown mounted inan aquarium with the return tube of a water recirculating system shownin phantom line.

FIG. 2 is an enlarged cross sectional view ofa portion of the deviceshown in FIG. I and taken substantially along line 2--2 of FIG. 3.

FIG. 3 is a top plan view of the device of FIGS. 1 and 2.

FIG. 4 is an enlarged section of a portion of the device in FIG. 2 takenalong line 4-4.

FIG. 5 is a cross sectional view of another form of the invention takensubstantially along line 5--5 of FIG. 6. The device is mounted in anaquarium and the return tube of a water recirculating system is shown inphantom line.

FIG. 6 is a top plan view of the device of FIG. 5. FIG. 7 is a bottomview of the device of FIG. 5. FIG. 8 is a perspective exploded view ofthe device shown in FIGS. 1-3.

FIG. 9 is a perspective view of the device shown in FIGS. 5-7.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION Theaerator of the present invention consists briefly of a venturi tube 6adapted for connection to a source of water 7; an air and waterreservoir 8 mounted adjacent the throat 9 of the venturi above thereservoir; a passageway 11 (sometimes referred to as a first passageway)connecting the water and air reservoir with the venturi throat andhaving a discharge port opening 11a substantially smaller than theventuri throat opening; and means 12 for adjusting the level of water inthe reservoir so that water and air will flow through the passagewaysuch that the meniscus 13 formed on the wall of the passage covers asubstantial portion of the opening in the passageway and intrudes uponthe portion 14 of the passageway which carries the air.

The device is preferably made of plastic for durability but can be madeof metal or other materials. It is connected to the outlet tube 16 of awater recirculating system by an elastic annular sleeve 17. The devicepreferably has a neck portion 18 dimensioned to fit stan dard flexibletubing and a shoulder 19 to prevent further insertion of the tubing.

The design of the venturi is standard and the purpose is to create a lowpressure zone in the throat so that air and water will be drawn throughthe passageway 11. The design of the venturi has not been found to becritical and the following dimensions are given only by way of example.The converging walls 21 are at an approximate angle of 22 below thecylindrical neck section 18. The divergent walls 22 are at an angle ofabout 7% to 8.

The passageway 11 connecting the throat and the reservoir is notcritical in size although it necessarily must be fairly small so thatthe meniscus can fill a substantial portion of the area of thepassageway through which air is moving. An opening of about 0.020 to0.030 inch has been found to work satisfactorily.

The water and air reservoir may be constructed in various ways. Theessential characteristic is that the water level of the reservoir mustbe maintained at least to the level of the passageway 11 so thatcontrolled amounts of water and air may pass therethrough. Re ferring toFIG. 1, the water and air reservoir consists of member 8 forming achamber 24 which is located adjacent the venturi forming a water tightfit therewith. The water level is indicated by the line 26. Air flows tothe reservoir through passage 25 and enters at a conveniently placedopening 27 in the top portion of the res ervoir. Normally the reservoirwill be placed above the level in the aquarium as shown in FIG. 1, butin an alternate form, the entire apparatus. including the reservoir canbe submerged below the level of the water by inserting an elongated tubeinto passage 25 to extend above the water surface in the manner of asnorkel.

In each form of the invention, there must be a method of filling thereservoir with a supply of water since the water is continually drawnthrough the passage 11. In FIG. 1, a small passage 31 (sometimesreferred to as a second passageway) is formed or drilled in theapparatus extending from an opening 32 at the upstream end of theventuri tube to an opening into the reservoir as at point 33. Preferablythe water is discharged below the normal water level of the reservoir.There are other means for filling the reservoir and they will bedescribed below.

The level of water in the reservoir may be controlled by eithercontrolling the intake of water or air. In FIGS. 1, 2 and 3, the controlmeans regulates the supply of water. TI-Ie device is constructed with athreaded opening 34 in which is inserted a threaded member 36 having aknurled manually engageable knob 37. A cone shaped needle valve 38 seatson a valve seat 39 located in the passageway 31 so as to regulate theflow of intake water to the reservoir by merely turning the knob 37.

To operate the device in FIGS. 1 and 2, the venturi tube discharge endis inserted below the surface 40 of the water in the aquarium and wateris caused to circulate through the tube 16 in the direction shown byarrow 41. Needle valve 38 is opened permitting water to flow throughpassage 31 and to fill reservoir 8 to the approximate level of theopening to passage 11. Air bubbles 42 are large at first but as thewater level rises at the opening 23, the bubbles will begin to getsmaller. The valve should not be opened so wide as to flood the opening.

The reason for the usually great number of uniformly tiny bubbles is notfully understood but it has been observed by tests that the desired sizeand quantity of I bubbles appears when the opening is so filled withwater that the meniscus 13 in the opening 23 covers a substantialportion of the remaining air opening 14. Note in FIG. 4 that the levelof the water in opening 23 is at point 44 and the top of the meniscus iswell above at lever 45. The forming of a meniscus is a well knownphenomenon in which the adhesive force between the water and walls ofthe device is greater than the cohesive force of the water. Anotherfactor is that it has been found that the surface tension at themeniscus is less than the surface tension at the normal water levelsurface 44. Thus it is believed that the air rushing through the openingbreaks the water surface tension at the surface of the meniscus, andthere is an infusion of air into the water at this point. It is alsobelieved that there is friction between the interfaces of the water andair, and the rushing water causes air to be drawn along the watersurface into the passageway 11. When the air reaches the end of thepassageway at discharge opening 11a, it meets a wall of fast movingwater in the venturi tube where it is drawn into the water; primarilythrough the meniscus where the surface tension of the water isrelatively less. If the air is regulated so that the air opening 14 isrelatively small, the device will form hundreds of tiny bubbles whichbreak at the water surface relatively noiselessly.

Another form of the invention is shown in FIGS. 5-7, and 9. Theidentical principle is used to form the bubbles but instead ofcontrolling the level of the reservoir by adjusting the amount of waterinflow, the amount of air is subject to adjustable control. The deviceconsists of a venturi tube 56 having upstream converging walls 57, anddownstream diverging walls 58 separated by a throat area 59. The anglesof the walls are the same as previously described for the device shownin FIGS. 1 and 2. The venturi has an upper cylindrical wall 61 formedwith a shoulder 62 for receiving a flexible sleeve 63 which is connectedto an outlet tube 64 in which water flows in the direction shown byarrow 66. A passageway 67 connects the throat of the venturi tube withthe reservoir 68 and is the same size as the passageway described inFIG. 1.

Instead of the reservoir being filled with water from above, the form ofthe invention shown in FIGS. 5 7 fills the reservoir with water frombelow. In specific, the reservoir has an opening 69 at its lower endwhich opens to the main body of water 71 which fills the aquarium. Thetop portion of the reservoir is enclosed by sidewalls 72 and top wall'73. A passageway 74 is formed in the device with an inlet 75 opening tothe atmosphere and. a discharge opening 76 opening to the air chamber 77in the reservoir. A threaded needle valve 78 opens and closes thepassageway 74 by seating on a valve seat 79 formed in the device. Thevalve is closed by rotating knurled knob 81. In order to preventclogging of the small passageway 67, it is desirable to place a filter83 in the inlet end of the reservoir. Because a relatively great amountof suction is formed in reservoir 68, it is necessary to either restrictopening 69 or place a relatively dense filter material in the openmg.

The operation of the device shown in FIGS. 5-7 is similar to theoperation of the device of FIGS. 1 and 2. The device is placed in theaquarium with the outlet 84 of the venturi tube submerged below thewater surface 86 of the aquarium. The filtered water enters through tube64 and causes the pressure to drop at the throat portion of the venturi,thus creating a suction through passageway 67. If the needle valve isclosed, water will rise in the reservoir; being taken from the aquariumthrough the inlet 69. The needle valve must be adjusted to leave justsufficient air to enter passage 74 so that the water level 87 will riseto the level of opening 88 so that the meniscus fills a significantportion of the air space left in the opening as shown in FIG. 4. The airbubbles 89 are formed in the same manner as previously described and thebubbles enter the venturi at discharge opening 90 of the passageway 67.The bubbles are discharged through opening 84 in the venturi tube andrise to surface 86.

It has been found that the tiny bubbles are more easily formed when asurfactant is added to the aquarium water The improved condition isbelieved due to the fact that the surfactant lowers the surface tensionof the water and the air enters the water in the passageways 1 1 and 67more easily because of the decreased surface tension. Another possibleexplanation is the fact that the surfactant makes the water a betterwetting agent which causes a greater meniscus to be formed in the firstpassageway; again permitting the air to enter the water more easilybecause of the decreased surface tension at the meniscus.

Several surfactants can be used; all of which must be non-toxic whenused in aquariums. One example is TWEEN 80 a trademark, which ispolyoxyethylene sorbitan monooleate. Between l and 2 drops of percentconcentrate per gallon of water works satisfactorily.

In both forms of the invention it has been found advantageous to locatethe walls of the water and air reservoirs in close proximity to theventuri tube. Whether the meniscus 91 formed at the passageway 11 inFIG. 2 or the meniscus 92 formed at the passageway 67 in FIG. 5 plays apart in the forming of the bubbles is not known. The inside wall 93 ofthe reservoir is preferably about 0.06 0.100 inches from the outerventuri wall 94. Note meniscus 95 on the reservoir wall.

Referring to FIGS. 5 and 7, the inner wall 72 is located 0.06 0.100inches from the outer wall 98 of the venturi causing a meniscus 92 toform. It is possible that air enters the water at the openings 23 and88. In order to achieve such close wallproximity, especially at thepassageway 11, the air valve mechanism and opening are separated asshown in FIG. 6. In both forms of the invention, greater quantities ofsmall bubbles can be formed by forming additional passageways betweenthe air and water reservoirs and the venturi tube.

I claim:

1. An aerator for an aquarium comprising:

a. a venturi tube adapted for connection to a source of water;

b. a water reservoir mounted adjacent the throat of said venturi;

c. means for supplying water to said reservoir;

d. an air reservoir;

e. means supplying air to said reservoir;

f. a first passageway connecting said air and water reservoirs with saidventuri throat and having an opening substantially smaller than thethroat opening; and

g. meansfor adjusting the air and water ratio so that water and air willflow through said first passageway such that the meniscus formed on thewall of said first passage constitutes a substantial portion of the airopening in said first passageway.

2. An aerator as described in claim 1 comprising:

a. means regulating the supply of water to said water reservoir.

3. An aerator as described in claim 1 comprising:

a. means controlling the supply of air to said air reservoir.

4. An aerator as described in claim 2 comprising:

a. a second passageway connecting said water reservoir and said sourceof water;

b. said means for adjusting the level of water in said water reservoirbeing operatively connected to said second passageway; and

c. said water reservoir being open to atmosphere.

5. An aerator as described in claim 3 comprising:

a. said water reservoir being operatively connected to the water in saidaquarium;

b. a closed air reservoir mounted above said water reservoir and open tosaid water reservoir; andc. said means for adjusting the levelof waterin said water reservoir includes an air passage connecting said airreservoir and the atmosphere and a valve operatively connected to saidair passage for re stricting the flow of air.

6. An aerator as described in claim 1 comprising:

a. air and water reservoirs being located below the water surface ofsaid aquarium; and

b. snorkel means connected to said air reservoir and extending above thewater surface of the aquarium to the atmosphere.

1. An aerator for an aquarium comprising: a. a venturi tube adapted forconnection to a source of water; b. a water reservoir mounted adjacentthe throat of said venturi; c. means for supplying water to saidreservoir; d. an air reservoir; e. means suppLying air to saidreservoir; f. a first passageway connecting said air and waterreservoirs with said venturi throat and having an opening substantiallysmaller than the throat opening; and g. means for adjusting the air andwater ratio so that water and air will flow through said firstpassageway such that the meniscus formed on the wall of said firstpassage constitutes a substantial portion of the air opening in saidfirst passageway.
 2. An aerator as described in claim 1 comprising: a.means regulating the supply of water to said water reservoir.
 3. Anaerator as described in claim 1 comprising: a. means controlling thesupply of air to said air reservoir.
 4. An aerator as described in claim2 comprising: a. a second passageway connecting said water reservoir andsaid source of water; b. said means for adjusting the level of water insaid water reservoir being operatively connected to said secondpassageway; and c. said water reservoir being open to atmosphere.
 5. Anaerator as described in claim 3 comprising: a. said water reservoirbeing operatively connected to the water in said aquarium; b. a closedair reservoir mounted above said water reservoir and open to said waterreservoir; and c. said means for adjusting the level of water in saidwater reservoir includes an air passage connecting said air reservoirand the atmosphere and a valve operatively connected to said air passagefor restricting the flow of air.
 6. An aerator as described in claim 1comprising: a. air and water reservoirs being located below the watersurface of said aquarium; and b. snorkel means connected to said airreservoir and extending above the water surface of the aquarium to theatmosphere.